1. Field of the Invention
The present invention relates to a high frequency discharge ignition device to be used mainly in an internal combustion engine.
2. Description of the Related Art
In recent years, problems relating to environmental conservation and fuel depletion have been raised, and responding to these problems also represents an urgent task in the automobile industry. As an example of a response thereto, there exists a method in which fuel consumption is improved through engine downsizing using a supercharger.
However, when a supercharger is used and a highly supercharged state is reached, pressure in an engine combustion chamber becomes extremely high even in a state where combustion is not occurring, making it difficult to generate a spark discharge for initiating combustion. As a solution to this, a state in which a spark discharge can be generated easily is created by narrowing the gap of a spark plug. However, when the gap of the spark plug is narrowed, quenching effect caused by the electrode part, that is, an effect where energy that allows a just generated spark to grow is depleted by the low-temperature electrode part, becomes more pronounced, which results in a decrease of startability or a combustibility.
In order to solve this problem, a method has been considered in which energy that exceeds the thermal energy depleted by the quenching effect is provided by spark discharge. For example, Japanese Patent No. 5250119 describes a high frequency discharge ignition device that enables a high-energy spark discharge to be formed by supplying, to a spark plug, high frequency energy having a high voltage and acquired as a result of coupling high frequency energy boosted by a booster circuit to a spark discharge generated by an ignition coil.